FIG. 8 shows the conventional connection structure of power generating elements 1, current-collector connectors 2, and external connection terminals 3 in a non-aqueous electrolyte secondary battery. In this non-aqueous electrolyte secondary battery, two power generating elements 1 of an elliptic cylindrical shape are connected in parallel.
Each power generating element 1 such as shown in FIG. 3 is configured by winding a positive electrode 1a and a negative electrode 1b with a separator 1c therebetween into an elliptic cylindrical shape. In the positive electrode 1a, the surface of a strip aluminum foil 1d to be used as an electrode substrate is supported with a positive active material; and in the negative electrode 1b, the surface of a strip copper foil 1e to be used as an electrode substrate is supported with a negative active material. These positive electrode 1a and negative electrode 1b are provided with non-coated portions, where the active material is not applied to one side-edge portions of the negative strip and to the other side-edge portions of the positive strip, thereby allowing the aluminum foil 1d and the copper foil 1e to be exposed in the non-coated portions. And, in the formation of the power generating element 1 by winding, these positive electrode 1a and negative electrode 1b are wound with being shifted in the opposite direction from each other along the winding axis, so that only the aluminum foil 1d at the side-edge portions of the positive electrode 1a protrudes from one end face of the elliptic cylindrical shape and only the copper foil 1e at the side-edge portions of the negative electrode 1b protrudes from the other end face.
The above-described two power generating elements 1, 1 are aligned horizontally so that the flat side of each elliptic cylindrical shape overlaps each other in an upright stance. And, at both sides of the end faces of these power generating elements 1, 1, each electrode is connected to the current-collector connectors 2, 2 of a ribbed plate type, respectively. The aluminum foil of the positive electrode 1a or the copper foil of the negative electrode 1b protruding from the end face of the power generating element 1 is held in each of the concave portions of a ribbed plate type, ultrasonic welding is performed, and hence, the electrodes are connected and fixed.
However, there arose a problem in that the use of the above-described structure made it difficult for the current-collector connector to be connected to the power generating element. Moreover, in case of a battery having a large capacity, it is necessary to make a plate thickness of the current-collector connector 2 thick enough for a large amount of electric currents to pass, thereby causing another problem of easy occurrence of defective welding when ultrasonic welding was performed on the thin aluminum foil or copper foil which was held in it.